The present invention relates generally to a method and apparatus for determining accurately the intravascular location of a catheter inside biological tissue, particularly within veins or arteries, and specifically within the vena cava.
The treatment of certain diseases of the human body often requires the short-term or long-term infusion of drugs, blood products, nutritional or other fluids into the patient's venous or arterial system. When it is necessary to administer these parenteral liquids, it is common practice to make a venipuncture with a cannula and then thread a sterile plastic catheter into the vein. Alternate techniques for vascular access include surgical cut-down or Seldinger entry with a dilator/sheath over a guidewire. For patenteral nutrition, cancer chemotherapy, and frequent antibiotic therapy, the outlet (or tip) of the catheter is positioned in areas of high volume blood flow to avoid damage to the lining (intima) along the blood pathway. The end-point for the intravenous catheter tip is often the superior vena cava. The catheter placement procedure is referred to as central venous catheterization (CVC), and growing experience has increased recognition of the need for accurate positioning of the catheter tip.
In current practice, the conventional method for confirming the correct placement of a therapeutic intravenous catheter within the superior or inferior vena cava is visualization with fluoroscopy or x-ray film. However, additional exposure of the patient and clinical staff to irradiation is a disadvantage, and unnecessary if an alternate method for locating were made available.
Thus, a need exists for providing realtime information for accurately determining the location of a catheter within a patient's body according to external anatomical landmarks which eliminates the cost, time, and hazards of radiation exposure and which does not require expensive, high technology equipment or personnel.